This invention relates to tractor feed printers and, in particular, to a parting tool for separating the guide strips on the sides of fan-fold paper from the main body of the paper.
The hard copy or printout from a computer can be produced by several different kinds of printers, e.g. laser or xerographic, dot matrix, or daisy wheel. A laser printer uses a stack of separate sheets of paper in a tray and has a complex paper handling mechanism to feed the sheets one at a time to the printing mechanism. The other kinds of printers use either a friction feed mechanism or a tractor feed mechanism for moving the paper past a print mechanism.
A friction feed mechanism pinches the paper between two rollers, one of which is driven by a small electric motor. The paper for a friction feed printer is either in single sheets or is continuous. By continuous is meant a roll of paper with rows of perforations across the width of the roll. The spacing of the rows determines the length of a page. The paper is folded along the perforations alternately in opposite directions, resembling a fan or accordion. A problem with friction fed, continuous paper is that the paper drifts out of alignment when more than a few pages are printed.
A tractor feed mechanism overcomes the problem of drift by using sprockets to engage holes in the paper. The paper for tractor feed printers is continuous, as described above, with a narrow guide strip on each side along the length of the paper. The guide strip has a plurality of regularly spaced holes for engaging the sprockets in the tractor feed mechanism to advance the paper. Each guide strip is typically one half inch wide and is separated from the sheet by a tear line or perforations.
Although the pages of a printout are often left joined end to end, the guide strips on the sides are usually removed. For example, storing a printout in a folder can be a problem because the paper is not a standard width with the guide strips. The paper cannot be punched for storage in a three ring binder because of the guide strips. Removing the guide strips page by page is a time consuming chore. Simultaneously removing the guide strips from one side of all of the pages often tears a page of the printout or tears the guide strips, leaving small segments that must be removed individually. Re-printing torn pages is a time consuming and unproductive activity.
Although the problem of removing the guide strips has been addressed in the prior art, the solutions proposed involve tearing the guide strips simultaneously from one side of a printout. For example, U.S. Pat. No. 4,529,113 discloses a clamp for holding the guide strips while they are torn from one side of the printout. U.S. Pat. No. 4,657,163 discloses a clamp having a wedge pressed against the printout at the perforations to promote tearing. U.S. Pat. No. 4,782,986 discloses a clamp with a pivoting upper jaw to facilitate separating the guide strips from the sheets. U.S. Pat. No. 4,886,198 discloses a blade and a recess on opposite sides of the perforations to facilitate tearing the guide strip from one side of the printout.
In view of the foregoing, it is therefore an object of the invention to provide a parting tool for shearing both guide strips simultaneously from tractor feed paper.
Another object of the invention is to provide a tool for continuously removing the guide strips from each sheet of paper as it comes from a tractor feed printer.
A further object of the invention is to provide a parting tool which can be attached to or be an integral part of the tractor feed mechanism of a printer.
Another object of the invention is to provide a parting tool which can be selectively disabled without being removed from a tractor feed mechanism.